Self-compensating load responsive brake assembly

ABSTRACT

A self-compensating brake assembly continually applies a braking or drag force on a rotating shaft in response to changes in weight on the shaft. A spring-biased bearing moves vertically relative to a carrier plate in response to changes in weight on the shaft it supports. An endless brake band is attached to a pivot arm with one end connected to the bearing support and the other end connected to the bearing member. The brake band, which continually engages a brakedrum rotating with the shaft, is connected to the arm between its ends. Therefore, the brake band support point moves a lesser vertical distance in proportion to the brake drum to provide tightening and loosening contact of the band in proportion to the weight on the shaft.

United States Patent [72] Inventor Walter William Lauer, Jr.

Canton, Ohio [21] Appl. No. 817,798

[22] Filed Apr. 21, 1969 [45] Patented Apr. 20, 1971 [73] Assignee The General Tire & Rubber Company [54] SELF-COMPENSATING LOAD RESPONSIVE 2,670,522 3/1954 Culpepper 2,877,963 3/1959 Hayden ABSTRACT: A self-compensating brake assembly continually applies a braking or drag force on a rotating shaft in response to changes in weight on the shaft. A spring-biased bearing moves vertically relative to a carrier plate in response to changes in weight on the shaft it supports. An endless brake band is attached to a pivot arm with one end connected to the bearing support and the other end connected to the bearing member. The brake band, which continually engages a brakedrum rotating with the shaft, is connected to the arm between its ends. Therefore, the brake band support point moves a lesser vertical distance in proportion to the brake drum to provide tightening and loosening contact of the band in proportion to the weight on the shaft.

BRAKE ASSEMBLY 4 Claims, 4 Drawing Figs.

52 us. c1 188/195, 242/156 [51] Int. Cl B601 8/18 [50] Field of Search 188/83, 195; 242/75.46, 156, 156.2

[56] References Cited UNITED STATES PATENTS 1,657,044 l/l928 Sipp 188/83 PATENTED M20 1971 SHEET 2 BF 2 INVENTOR. WALTER w. LAUER, JR.

A T TORNE Y BACKGROUND OF THE INVENTION In handling material in elongated sheet or web form, the material is often supplied from a roll or shell about which the sheet has been previously wound, usually for storage purposes. Depending upon the particular material and the type of handling involved, the material is normally pulled or withdrawn from the roll as needed. The withdrawal may be continuous or intermittent depending upon the purposes for which the material is used.

For example, the paper and textile industries process large quantities of materials from rolls of this type. In the rubber and plastics industry, carcass fabric for tires and plastic sheet are often processed using storage or feed rolls of this type.

Whatever the type of material supplied, the particular supply roll is normally mounted on a shaft which rotates in response to forces necessary to unwind the sheet from the roll.

The rotatable shafts which support the rolls are normally provided with a brake to prevent overrunning or freewheeling of the roll once rotation is started due to the unwinding of the sheet material. In other words, the roll is controlled to rotate at a substantially constant speed in response to a particular withdrawal force. Once the withdrawal force is removed, rotation stops smoothly due to the dragging force which was continually being applied by the brake.

it can be seen that the braking force to be applied to the rotating shaft is dependent upon the rotational inertia of the roll or shell of material mounted thereon. To prevent the roll from overrunning when the withdrawal force is removed, the magnitude of the braking force must be sufficient to overcome the inertia of the roll at the moment the force is removed.

Since the rotational inertia of the roll depends upon the weight of the roll, the inertia changes as more and more material is withdrawn from the roll. Thus, the drag force sufficient to prevent overrunning of a full or nearly full roll will be too great for a roll which is nearly empty. As the roll empties an overly effective force, i.e. a force to prevent overrunning of a fuller roll, can cause unnecessary motor loads or undue stretching or tearing of the material. 0n the other hand, if a brake is set to prevent overrunning of a nearly empty roll, then satisfactory retardation of fuller rolls is not possible and overrunning can cause tangling of the sheet material.

It is seen from the foregoing that a simply designed brakemechanism which compensates for continuing weight changes on the roll would be a most effective and desirable means to remedy these problems.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a brake assembly for a rotating shaft which is self compensating in response to the weight carried by the shaft.

it is another object of the present invention to provide a brake assembly which is effective in preventing overrunning of a rotating shaft by applying a retarding brake force which varies in proportion to the weight on the shaft.

It is yet another object of the present invention to provide a simply designed brake which can apply a continual drag force on a rotating shaft, the force changing in magnitude in response to changes in the weight supported by the shaft.

The brake assembly achieves the foregoing objects by featuring an endless brake band which is adapted to tighten or loosen its contact with a brakedrum on a rotating shaft in proportion to a spring-biased bearing member which moves vertically in response to the weight on the shaft it supports. The brake band is attached between the ends of a pivot art, one end of which is secured to the movable bearing member and its supported shah, while the other end is attached to a stationary plate which carries the movable bearing member. Thus, the movable bearing and shaft will move vertically in accordance with weight on the shaft. The point on the pivot arm where the brake band is secured will move a vertical distance less than that moved by the bearing, and thus cause a tightening or loosening of the band on the drum depending on the direction of vertical movement.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation of a preferred embodiment of the brake assembly according to the present invention shown operatively associated with a rotatable shaft, with parts shown in section and omitted.

FIG. 2 is a view of the brake assembly shown in FIG. 1 taken along lines 2-2 thereof.

FIG. 3 is a view similar to FIG. 2, but taken along lines 3-3 of FIG. 1.

FIG. 4 is a plan view of the brake assembly as shown in FIG. 3, with portions broken away, omitted and shown in section.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT Referring to FIGS. I through 4 of the drawings wherein like reference numerals are intended to refer to like structure throughout the several views, a portion of a frame, generally designated as 10, is shown supporting a cantilever shaft 20 mounted at one end in a typical pillow block type bearing member 22. The shaft 20 can be freely rotatable in bearing member 22 or positively rotated by a suitable drive (not shown). The free or unsupported end of shaft 20 is typically designed to slidably receive, and support for rotation therewith, a roll or shell of material in continuous sheet or web form (not shown).

A typical cylindrical brakedrum 30 is shown keyed or otherwise secured to shaft 20 and axially spaced from bearing 22. The brakedrum may be of any suitable material such as hot-rolled steel. The outer periphery of drum 30 may be smooth as shown or treated in some way to enhance its frictional characteristics for contacting a brake band. On the other hand, the drum may be cast which could provide a rougher peripheral surface than that shown, if this is desirable.

Axially spaced from drum 30 is a U-shaped carrier plate 35 which straddles shaft 20 with the ends of its vertically extending legs welded or otherwise secured to a horizontally disposed support plate 36 provided with a pair of bolt holes 37. As seen particularly in FIG. 4, plate 36 also is U-shaped to provide an access opening for a bearing member to be later described. Bolts 12 register through holes 37 to secure mounting plate 36 and its attached carrier plate 35 to frame 10. Plates 35 and 36 can be of any typical material, such as hot rolled steel. The opening 34 in U-shaped carrier plate is specially adapted to mount a second bearing member generally designated as 24.

The bearing member 24, which supports shaft 211 for rotation therein, is provided with a pair of vertical grooves or tracks 25 which slidably engage the inside edges of the vertical legs of carrier plate 35. The support extension 26 of bearing 24 is provided with an opening 27 to receive a vertically disposed alignment pin 14 one end of which is pressed or otherwise secured into plate 35 as shown. Between bearing extension 26 and the bottom edge of opening 34 in plate 35 are a pair of spaced metal discs 21, one contacting the underside of bearing extension 26, the other contacting plate 35. The discs 21 are each provided with a central opening for passage of alignment pin 14. Between discs 21 is a bellowstype spring member 15', one end of which contacts the underside of the upper disc 21, the other end resting on the upper side of lower disc 21.

The spring member 15 is preferably composed of a series of disc springs 17 specially stacked to produce the proper load and deflection characteristics required to support the bearing 24 and its supported shaft 20. However, other equally suitable springs may be used such as one of the other kinds of commercially available bellows-type springs. Also, a coil spring may be used if desired. The spring discs 17 each are provided with central openings to permit passage of alignment pin 14 therethrough.

From the foregoing structure, it can be seen that the entire bearing 24 is spring biased on carrier plate 35 and guided by means of grooves 27 and alignment pin 14 so that the bearing and its supported shaft can move vertically relative to the plate 35 which is secured to frame 10.

A rectangular rider plate 40 is secured to one face of the movable bearing 24 by bolts 11 fitted through the comers of bearing 24. The bolts 11 are preferably threaded at the ends thereof and are held in tapped holes in rider plate 40. Of course, depending on the distance between the drum 30 and the plate 40, it is possible that bolts 11 can extend beyond plate 40 and be fitted with nuts (not shown). The rider plate, in any event, is held flush against one face of the bearing 24 so that it also will move with the bearing 24 and its supported shaft 20. The rider plate 40 is provided with a suitable opening to allow passage of the shaft therethrough.

A channel-shaped pivot arm 45 is shown with one end secured to rider plate 40 by means of a first clevis pin 16 extending through a suitable opening in the arm 45 and into the rider plate 40. A suitable number of fiat washers 19 are positioned between the face of rider plate 40 and the arm 45.

The arm 45, shown extending toward the left in FIGS. 3 and 4, is secured at its other end to a rigid toggle member 47 by a second clevis pin 17 extending through arm 45. The toggle is adjustable to different lengths by means of threaded arms 48 connecting to a coupling member 49. The lower end of toggle member 45 is secured to carrier plate 35 by a bolt 13 registering in a bolt hole 38. A similar hole 38' is provided on the right-hand side of plate 35 for purposes described hereinafter. Any suitable connecting structure may be provided in order to secure the lower end of toggle member 45 to carrier plate 35. For example, the lower threaded arm 48 may tenninate in a circular loop, such as 47 (FIG. 4), through which a hollow connecting arm 49 may pass to extend to the face of plate 35. A threaded bolt, such as 13, may then be fitted through the loop and connecting arm and turned into a tapped hole such as 38 in plate 35. How the toggle member 45 is secured to plate 35 is not particularly critical. It is important only that the left end of arm 45, as seen in FIGS. 3 and 4, is secured in some manner to carrier plate 35.

Between the ends of pivot arm 45, through which clevis pins 16 and 17 extend, is a third clevis pin 18, also extending through the arm. Each pin 17, l8, 19 are similar in construction and extend through pivot arm 45 in mutually parallel relationship.

The pin 18 supports the end of a tear-shaped endless brake band, generally designated as 50, which engages brakedrum 30. The brake band 50 is preferably made substantially rigid by a metal strap 52 which is secured to a pair of support arms 54 which meet for support by pin 18. A suitable brake lining 56, such as leather, is bonded to a portion of the inner surface of metal strap 54. While leather has been found to be an efiective material for frictionally contacting the outer periphery of brakedrum 30, it is understood other types of commercially available brake lining material would be equally as effective for this purpose. For example, it could be possible to design a brake band which employs one of the currently popular asbestos-type lining materials as an equally effective alternate to that shown.

It should be noted that in the preferred embodiment depicted in the drawings the shaft 20 and attached brakedrum are indicated as rotatable counterclockwise. The structural design just described is particularly suited for this rotational direction. If, in fact, the shaft 20 and its attached drum are to be rotated clockwise, the assembly shown should preferably be modified to what could be termed a mirror image of that shown in FIGS. 1 through 4. In other words, the pivot arm should extend to the right in FIGS. 3 and 4, rather than as shown. The critical pieces i.e. the arm 45, rider plate 40 and carrier plate are designed specially so as to provide a brake assembly capable of easy modification whether the shaft rotates clockwise or counterclockwise.

As mentioned previously, carrier plate 35 is provided with another opening 38 suited for the attachment of toggle member 45 on the right side of shaft 20 rather than the left as shown in the drawings. Rider plate 40 and pivot arm 45 can be simply turned around and the brake assembly constructed with the pivot arm 45 extending from plate 40 toward the right rather than the left. It can be seen that the designs of rider plate 40 and pivot arm 45 are particularly suited for constructing the brake for use no matter which way the shaft and drum is to rotate.

In order to describe the operation of the brake assembly according to its preferred embodiment, it is assumed that the shaft 20 supports for rotation a fully or nearly full roll or shell of sheet material previously wound thereon. The shaft will deflect or pivot about the bearing 22, as shown to an exaggerated degree in phantom outline in FIG. I. The shaft will pivot because the spring-biased bearing 24 is slidable within stationary carrier plate 35. Because brakedrum 30 is secured to shaft 20 and rider plate 40 is secured to bearing 24, these two members also move downwardly in direct response to the weight on shaft 20. The end of pivot arm 45, which is attached to rider plate 40 by pin 16 moves vertically a distance equal to the distance moved by bearing 24. The opposite end of pivot arm 45 does not move vertically, but only pivots about clevis pin 17, because it is secured to stationary carrier plate 35. The portion of the pivot arm 45 carrying pin 18, which is between the locations of pins 16 and 17, will move vertically a distance less than the distance moved by pin 16. In other words, the drum 30 moves a given distance in response to a particular weight while the pin 18 which supports the brake band 50 moves less than that given distance. This differential movement causes a tightening of brake band 50 around drum 30. Through a proper initial adjustment of the position of the stationary end of pivot arm 45 by means of toggle member 47, this tightening of the band 50 on drum 30 due to the weight of the nearly full roll causes a braking force on the shaft 20 of sufiicient magnitude to prevent the roll from overrunning for that particular weight.

As sheet material is intermittently or continuously withdrawn from the roll carried by shaft 20, the weight on the shaft 20 becomes less causing the shaft 20, drum 30, springmounted bearing 24, its attached rider plate 40 and the movable end of pivot arm 45 to rise a given distance. This causes the pin 18 in pivot ann 45 to rise a lesser distance. Thus, the brake band loosens it contact with brakedrum 30 causing a braking force of lesser magnitude than that applied when the roll was full or nearly full.

It can be seen from the foregoing that the brake assembly will continually compensate for weight changes on the shaft and thus at any given time apply a braking force necessary to overcome possible overrunning of the supply roll according to its weight at that time.

lclaim:

1. A self-compensating brake assembly for continually applying a weight responsive braking force to a rotating shaft joumaled in at least one fixed bearing relative to which said shaft pivots in response to a variable weight on said shaft, said brake assembly comprising a carrier plate, a bearing member for said shaft resiliently supported on said carrier plate for vertical movement relative thereto, said carrier plate and bearing member adapted to support said shaft at a given distance from said fixed bearing, a pivot arm, first means connecting one end of said arm to said carrier plate, second means connecting the other end of said arm to said bearing member, an endless brake band, a brakedrum adapted to be mounted on said shaft for rotation therewith, said endless brake band having a friction surface adapted to engage a substantial portion of the periphery of said brakedrum when mounted on said shaft, said brake band connected to said pivot arm at a selected point between said ends thereof.

2. The assembly defined in claim 1 wherein said bearing member is resiliently supported on said carrier plate by a spring means.

4. The assembly as defined in claim 3 wherein said bearing member is resiliently supported on said carrier plate by a spring means. 

1. A self-compensating brake assembly for continually applying a weight responsive braking force to a rotating shaft journaled in at least one fixed bearing relative to which said shaft pivots in response to a variable weight on said shaft, said brake assembly comprising a carrier plate, a bearing member for said shaft resiliently supported on said carrier plate for vertical movement relative thereto, said carrier plate and bearing member adapted to support said shaft at a given distance from said fixed bearing, a pivot arm, first means connecting one end of said arm to said carrier plate, second means connecting the other end of said arm to said bearing member, an endless brake band, a brakedrum adapted to be mounted on said shaft for rotation therewith, said endless brake band having a friction surface adapted to engage a substantial portion of the periphery of said brakedrum when mounted on said shaft, said brake band connected to said pivot arm at a selected point between said ends thereof.
 2. The assembly defined in claim 1 wherein said bearing member is resiliently supported on said carrier plate by a spring means.
 3. The assembly defined in claim 1 wherein said first means is adjustable to provide selective positioning of said one end of said arm relative to said carrier plate.
 4. The assembly as defined in claim 3 wherein said bearing member is resiliently supported on said carrier plate by a spring means. 